Of course wear your seatbelt. It's just absurd that law requires individuals to do so.
I can legally juggle chainsaws as a complete novice, yet I have no say in the matter of wearing a seatbelt. I can fly an ultralight aircraft with no experience and no seatbelt legally, but cannot choose not to wear a seatbelt in a vehicle.
Still, I see the argument for enforcing safety, and am thankful for the lives it has saved. I'm torn between protecting stupid people from themselves, and maximizing choice (freedom).
Concerning bus safety, it's orders of magnitude safer than passenger vehicles. I feel no need to wear a seatbelt, as the risk is sufficiently low.